The invention relates to the field of gene technology and is concerned with recombinant DNA molecules, which contain a nucleotide sequence coding for a protein or polypeptide having fibrinogen-binding activity. Moreover the invention comprises micro-organisms (including viruses) containing the aforesaid molecules, and the use thereof in the production of the aforesaid protein or polypeptide and their use in biotechnology. Further, the present invention comprises diagnostic and therapeutic uses of said new protein, e.g. compositions for active and/or passive immunisation.
During the last decade, the coagulase-negative staphylococci (CNS) have attracted an increasing attention. Along with the development of human and veterinary medicine, the number of susceptible hosts have increased. Advanced surgery, an increased use of bio-materials, medication with cytostatics, antibiotics and other drugs together with an increased frequency of antibiotica resistant strains of CNS have increased the susceptibility of the host. Concerning the veterinary importance of the CNS it is known that they can cause e.g. both sub-clinical and clinical inflammation in the bovine udder. The existence of bacteria that bind specifically to fibrinogen has been known for many years. The role of fibrinogen binding in the interaction process between the host and Staphylococcus aureus is still not clear but the fibrinogen-binding has been considered as one potential virulence factor of this species for instance in endocarditis (Moreillon et al 1995). No protein with fibrinogen binding properties has hitherto been described originating from CNS. However, the present invention describes the characterization and isolation of such protein using gene cloning. Furthermore, the invention describes different methods to measure the fibrinogen binding activity on cells of CNS and the use of this protein in biotechnology.
Generally, it might be difficult to obtain a homogeneous and a reproducible product if such a binding protein was prepared from staphylococcal cells directly. Moreover staphylococci are pathogenic and need complex culture media, which involves complications in large-scale cultures. There is thus a need for a new method for producing a fibrinogen binding protein (or fragments thereof).
The present invention discloses a new fibrinogen binding protein called FIG, a DNA molecule encoding said protein and applications for their use, according to the attached claims. Importantly, the present invention fills the long felt need of providing methods and means for diagnosing, type-determination, treatment and prevention of infections, caused by coagulase negative bacteria.